Compressor inlet control system



Dec. 27, 1955 J. F. SHUMAKER 2,728,517

COMPRESSOR INLET CONTROL SYSTEM Filed April 28. 1950 b TO ENGINECARBURETOR ATTORNEYS CGMPRESSGR INLET NTROL SYSTEM John F. Shumaker,Elyria, ()hio, assignor to Bendix- Westinghouse Automotive Air ilrakeCompany, Elyria, Ohio, a corporation of Delaware Application April 28,1950, Serial No. 158,782

Claims. (Cl. 230-46) This invention relates to fluid pressure systemsand more particularly to a novel arrangement for controlling theapplication of fluid to a compressor inlet.

At the present time, it is quite common to utilize on various types ofmotor vehicles, an engine driven compressor for the purpose of providinga source of compressed air for the operation of brakes, clutches,transmissions and/ or various of the other vehicle controls oraccessories. in such installations, it is also usual to provide sometype of filtering device for the inlet of the compressor in order toeliminate the entrance of dirt, grit, etc., into the compressorcylinder. in order to simplify such engine-driven compressorinstallations it has been proposed that the engine air cleaner or filterbe used to not only filter the air conducted to the engine carburetor,but to also filter the air fed to the compressor intake connection. Thusthe compressor intake would be connected to the conduit or connectionleading from the engine air filter to the carburetor. While such anarrangement avoids the necessity of utilizing a separate air filter forthe compressor, it has the disadvantage of subjecting the compressor toa source of subatmospheric pressure when the compressor is unloaded, dueto the engine suction created in the connection between the filter andengine carburetor. it has been found that in such installations, thesubatmospheric pressure or suction which is present in the compressorcylinder during periods of operation of the compressor in an unloadedcondition, cause an excessive amount of oil to be passed by the pistonrings, thereby resulting in depletion of the oil supply, the creation ofcarbon, and the occurence of all the other undesirable features whichaccompanying excessive oilpassing in a compressor.

It is accordingly one of the objects of the present invention to providea compressor inlet control system which is so constituted as to avoidthe above mentioned disadvantages and objections.

Another object is to provide a compressor installation wherein thecompressor inlet is connected with theair inlet of the engine andwherein the effects of engine suction in the compressor cylinder whenthe compressor is unloaded are completely avoided.

A further object is to provide a novel compressor control system of theabove character wherein the compressor intake is connected directly withthe atmosphere during all periods of operation of the compressor in anunloaded condition, such a system thereby avoiding the objections whichresult from connecting the compressor cylinder of an unloaded compressorto the engine intake.

Still another object comprehends in a system of the foregoing type, anovel control for automatically switching the compressor intake from theengine intake connection directly to atmosphere when the compressor isunloaded.

A still further object is to provide a novel fluid pressure system whichincludes a compressor, a reservoir and a governor, the compressor intakebeing normally connected with the engine intake, and the governorfunctioning in accordance with a predetermined rise in pressure in thereservoir to automatically disconnect the compressor intake from theengine intake and to automatically connect the said compressor intakedirectly with the atmosphere.

Other objects and novel features of the invention will appear more fullyhereinafter from a consideration of the following detailed descriptionwhen taken in connection with the accompanying drawing which illustratesone form of the invention. It is to be expressly understood however,that the drawing is utilized for purposes of illustration only and isnot to be taken as a definition of the limits of the invention,reference being bad for this purpose to the appended claims.

In the drawing, wherein the invention is diagrammatically illustrated,certain parts being shown in section, an engine driven compressor 10 isadapted to supply air under pressure to a reservoir 12 through a conduit14, such pressure being shown as being available for the application ofvehicle brakes. For this purpose, a brake valve 16, of any suitableconstruction such as for example that shown in the patent to W. J.Andres et al. No. 2,133,275, dated October 18, 1938, is connected withthe reservoir 12 by a conduit 18 and is adapted to control the supply ofcompressed air through a connection 20 leading to the various brakechambers, not shown. Loading and unloading of the compressor it) may beeft'ected in any suitable manner, such as by the use of a governor 22which may be constructed as shown in the patent to B. S. Aikman, No.1,754,218, dated April 15, 1930, such governor being respectivelyconnected with the reservoir 12 and with an unloading mechanism 24associated with the compressor, as by means of a conduit 26 and anunloader conduit 28.

From the above construction, it will be understood that the compressorit) operates to furnish compressed air to the reservoir 12 for theoperation of the vehicle brakes and any of the other accessories orcontrols of the vehicle. Also, until the pressure in the reservoir 12attains a predetermined value, the unloader conduit 28 Will be open toatmosphere at the governor 22, the compressor under these conditionsoperating in a loaded condition. As soon however, as the reservoirpressure reaches the cutout value for which the governor 22 is set, thelatter operates to connect conduits 26 and 28 in order to supply fullreservoir pressure to the unloading mechanism 24. When this oc curs, thelatter mechanism operates to either maintain the inlet valves of thecompressor open, or to establish communication between the cylinders ofthe compressor, or to otherwise render the compressor inoperative tofurnish the resevoir 12 with compressed air. Under these conditions, thecompressor 10 is unloaded, and this action will continue until thereservoir pressure drops to the cut-in pressure for which the governor22 is set. As soon as this occurs, the governor 22 will operate toexhaust the conduit 28 and the unloading mechanism 24 will return to itsformer position in order to load the compressor and enable it to againfurnish compressed air to the reservoir 12.

One of the important features of the invention resides in the control ofthe air conducted to the compressor intake 30 so that the intake airwill be filtered through the air filter of the vehicle engine. Suchfilters are highly efiicient and of generous capacity and henceeffectively prevent the entrance of dirt and other foreign matter intothe compressor. Since however, the engine air filter is constantlysubjected to the suction action of the engine, the compressor cylinderswill be likewise subjected to this suction action. When the compressoris loaded, the suction conditions do not adversely affect the operation.The suction action, under unloading conditions however, reduces thepressure in the compressor cylinders and results in undesirableoil-passing. In order to overcome this undesirable result, the inventionprovides an automatically operable mechanism whereby the compressorintake 30 is provided with a direct atmospheric connection when thecompressor is unloaded. This mechanism is moreover arranged as toautomatically reconnect the compressor intake with the engine filter assoon as the compressor is again loaded.

In order to effect the foregoing, the vehicle engine is provided withthe usual air passage 32 which conducts atmospheric air to the enginecarburetor through a filter 34, and the compressor intake 30 isconnected to the passage 32 through conduits 36 and 38 whenever thecompressor is loaded. On the other hand, when the compressor isunloaded, the invention provides a valve device 40 which operatesautomatically to switch the intake 30 from the conduit 38 to anatmospheric connection 42, thereby avoiding the creation of a lowpressure condition in the compressor cylinders during periods ofoperation in an unloaded condition. Such device also operatesautomatically to re-establish the communication between the intake 30and the passage 32 as soon as the compressor is loaded.

More particularly, and as shown, the valve device 40 comprises a centralcasing portion 43 provided with a partition 44 forming upper and lowerchambers 46 and 48 which are respectively connected with the conduits 38and 36. An opening 50 in the partition 44 normally serves to connect thechambers 46 and 48 when the compressor is loaded so that under theseconditions, the air intake is connected with the engine air passage 32.A pressure responsive valve is provided for controlling the opening 50,and as shown, includes a valve element 52 carried by a diaphragm 54, thelatter forming with a top casing portion 56, a control chamber 58 whichis connected at all times with the unloader conduit 28 through aconnection 60. As is illustrated, the diaphragm 54 is normally urged asby a spring 55, against a stop 62, carried by the casing portion 56, soas to maintain the valve 52 in open position. However, as will bereadily understood, as soon as the governor 22 cuts out and theunloading conduit 28 is charged with reservoir pressure, such pressurewill be conducted to the control chamber 58, as well as to the unloadingmechanism 24, in order to close the valve 52 and interrupt communicationbetween the compressor intake 30 and the air passage 32. When thisoccurs, the lower end of the valve 52 engages the upper portion of avalve 64 and moves the latter against the tension of a spring 65 to openposition, whereby the chamber 48 is connected through opening 66 to achamber 68 formed by a lower casing portion 79. Since the chamber 68 isopen to atmosphere through the atmospheric connection 42, it will bereadily understood that when the compressor is unloaded, the intake 30is switched from the suction passage 32 to the atmospheric connection42. It will likewise be seen that when the compressor is again loadedand the chamber 58 is exhausted to atmosphere through the governor 22,the valve 52 will return to the position illustrated, through the actionof the spring 55, While the valve 64 will be closed by the spring 65.Thus, the compressor intake 30 will be switched to the suction passage32 and will remain connected thereto until the governor 22 againoperates to charge the control chamber 58 and engage the unloader device24 upon a predetermined rise in reservoir pressure.

In operation, the parts will occupy the positions illus trated in thedrawing until the pressure in the reservoir 12 attains the cut-outpressure for which the governor 22 is set. Under these conditions, thecompressor 10 functions in a loaded condition and the compressor in take30 draws its air supply from the suction passage 32 by way of conduit38, chamber 46, port 50, chamber 48 and conduit 36. Thus the intake airlead to the compressor is subjected to the filtering action of theengine filter 34 and all danger of the entrance of dirt and otherforeign matter into the compressor cylinders will be avoided. As wellunderstood in the art, the supply of fluid pressure in the reservoir 12is available for the operation of the vehicle brakes throughmanipulation of the brake valve 16, and is likewise available for theoperation of any of the other vehicle controls or accessories byproviding suitable connections to the conduit 18, not shown.

As soon as the reservoir pressure attains the cut-out value of thegovernor 22, the latter operates to disconnect the conduit 28 from theatmosphere and to connect the conduit 26 with the conduit 28. Fullreservoir pressure will then be conducted to the unloader mechanism 24in order to unload the compressor. Simultaneously therewith, the chamber58 of the valve device 40 is charged with reservoir pressure through theconduit 60, this action causing the diaphragm 54 and the valve 52 to bemoved downwardly against the tension of the spring 55 in order to closethe port 50 and interrupt communication between the engine intake 30 andthe suction passage 32. As the valve 52 moves to its closed position,the valve 64 will be opened in order to switch the intake connection 30to the atmospheric opening 42. Thus during unloading of the compressor,the compressor cylinders will not be subjected to the engine suction andall danger of oil-passing in the compressor will be avoided.

As soon as the reservoir pressure drops to the cut-in pressure of thegovernor 22, the latter will function to connect the unloader conduit 28to the atmosphere. When this occurs, the unloader mechanism 24 functionsto load the compressor and the parts of the valve device 40 will returnto the positions illustrated. Thereupon, the atmospheric connection 42will be closed by the valve 64 and the compressor intake 30 will bereconnected to the suction passage 32. Thereafter, during operation ofthe compressor in its loaded condition, the intake air for thecompressor will be drawn through the engine filter 34.

While one embodiment of the invention has been illustrated and describedherein with considerable particularity, it will be understood by thoseskilled in the art that various modifications may be resorted to withoutdeparting from the spirit of the invention. Reference will therefore behad to the appended claims for a definition of the limits of theinvention.

What is claimed is:

1. A compressed air system comprising a compressor having an inlet andan outlet, a reservoir for the storage of air compressed by saidcompressor, conduit means constantly connecting said outlet andreservoir at all times, means including a normally open valve forconnecting the inlet with a source of subatmospheric pressure, means forconnecting said inlet with the atmosphere, a normally closed valve insaid last named means, unloading mechanism for said compressor, aconduit connecting said unloading mechanism with said reservoir, agovernor in said conduit operable to conduct compressed air from thereservoir to the unloading mechanism to unload the compressor when thepressure in said reservoir rises to a predetermined value and pressureresponsive means for closing the first valve and for opening the secondvalve to transfer the inlet from the source of subatmospheric pressureto the atmosphere when the compressor is unloaded.

2. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, means including a normally open valve forconnecting the inlet with a source of subatmospheric pressure, means forconnecting said inlet with the atmosphere, a normally closed valve insaid last named means, and means operable upon a predetermined rise inpressure in said reservoir for closing the first valve and for openingthe second valve to transfer the inlet from the source of subatmosphericpressure to the atmosphere.

3. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, means constantly connecting said outlet andreservoir at all times, a conduit for conducting filtered air to theintake of an internal combustion engine, means including a normally openvalve for connecting the inlet with said conduit, means for connectingsaid inlet with the atmosphere, a normally closed valve in said lastnamed means, and means for closing the first valve and for opening thesecond valve to transfer the inlet from the conduit to the atmosphere.

4. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, means constantly connecting said outlet andreservoir at all times, a conduit for conducting filtered air to theintake of an internal combustion engine, means including a normally openvalve for connecting the inlet with said conduit, means for connectingsaid inlet with the atmosphere, a normally closed valve in said lastnamed means, and means operable upon a predetermined rise in pressure insaid reservoir for closing the first valve and for opening the secondvalve to transfer the inlet from the conduit to the atmosphere.

5. A compressed air system comprising a compressor having an inlet andan outlet, a reservoir for the storage of air compressed by saidcompressor, conduit means constantly connecting said outlet andreservoir at all times, a pair of separate intake connections forconducting air to said inlet, means including a normally open valve forconnecting the inlet to one of said connections, means for connectingthe inlet with the other of said connections, a normally closed valve insaid last named means, unloading mechanism for said compressor, aconduit connecting said unloading mechanism with said reservoir, agovernor in said conduit operable to conduct compressed air from thereservoir to the unloading mechanism to unload the compressor when thepressure in said reservoir rises to a predetermined value and pressureresponsive means for closing the first valve and for opening the secondvalve to transfer the inlet from the one connection to the otherconnection when the compressor is unloaded.

6. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, a pair of separate intake connections forconducting air to said inlet, means including a normally open valve forconnecting the inlet to one of said connections, means for connectingthe inlet with the other of said connections, a normally closed valve insaid last named means, and means operable upon a predetermined rise inpressure in said reservoir for closing the first valve and for openingthe second valve to transfer the inlet from the one connection to theother connection.

7. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, means including a normally open valve forconnecting the inlet with a source of subatmospheric pressure, means forconnecting said inlet with the atmosphere, a normally closed valve insaid last named means, a normally inactive pressure responsive deviceconnected with said normally open valve, and means for subjecting saidpressure responsive device to reservoir pressure when the pressure inthe latter reaches a predetermined value for closing the first valve andfor opening the second valve to transfer the inlet from the source ofsubatmospheric pressure to the atmosphere.

8. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, means constantly connecting said outlet andreservoir at all times, a conduit for conducting filtered air to theintake of an internal combustion engine, means including a normally openvalve for connecting the inlet with said conduit, means for connectingsaid inlet with the atmosphere, a normally closed valve in said lastnamed means, a normally inactive pressure responsive device connectedwith said normally open valve, and means for subjecting said pressureresponsive device to reservoir pressure when the pressure in the latterreaches a predetermined value for closing the first valve and foropening the second valve to transfer the inlet from the conduit to theatmosphere.

9. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, a pair of separate intake connections forconducting air to said inlet, means including a normally open valve forconnecting the inlet to one of said connections, means for connectingthe inlet with the other of said connections, a normally closed valve insaid last named means, a normally inactive pressure responsive deviceconnected with said normally open valve, and means for subjecting saidpressure responsive device to reservoir pressure when the pressure inthe latter reaches a predetermined value for closing the first valve andfor opening the second valve to transfer the inlet from the oneconnection to the other connection.

10. A fluid pressure system comprising a compressor having an inle andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, a pair of separate intake connections forconducting air to said inlet, means including separate valves forselectively connecting the inlet to one or the other of saidconnections, fluid pressure actuated means for controlling said valves,and means responsive to a predetermined rise in reservoir pressure toconnect said fluid pressure actuated means with said reservoir.

11. A compressed air system for use on a vehicle having an internalcombustion engine provided with a conduit for conducting filtered air tothe engine intake, comprising a compressor having an inlet and anoutlet, a reservoir, a conduit constantly connecting said outlet andreservoir at all times to deliver compressed air from the compressoroutlet to the reservoir, means including a normally open valve forconnecting the compressor inlet with the conduit to the engine wherebysaid compressor is supplied with filtered air at subatmospheric pressureduring operation of the engine, means for conntcting the compressorinlet with the atmosphere, a normally closed valve in said last-namedmeans, a pressure responsive element movable to close the normally openvalve and to open the normally closed valve, and means operable when thepressure of the compressed air in the reservoir reaches a predeterminedhigh value to subject the element to reservoir pressure to move saidelement to close the normally open valve and to open the normally closedvalve.

12. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, means including a normally open valve forconnecting the inlet with a source of subatmospheric pres sure, meansfor connecting said inlet with the atmosphere, a normally closed valvein said last named means, and means for closing the first valve and foropening the second valve to transfer the inlet from the source ofsubatmospheric pressure to the atmosphere, said last named meanscomprising a fluid pressure actuator and a governor operable upon apredetermined rise in pressure in said reservoir for subjecting saidactuator to reservoir pressure.

13. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir means constantly connecting said outlet andreservoir at all times, a conduit for conducting filtered air to theintake of an internal combustion engine, means including a normally openvalve for connecting the inlet with said conduit,

means for connecting said inlet with the atmosphere, a normally closedvalve in said last named means, and means for closing the first valveand for opening the second valve to transfer the inlet from the conduitto the atmosphere, said last named means comprising a fluid pressureactuator and a governor operable upon a predetermined rise in pressurein said reservoir for subjecting said actuator to reservoir pressure.

14. A fluid pressure system comprising a compressor having an inlet andan outlet, a reservoir, conduit means constantly connecting said outletand reservoir at all times, a pair of separate intake connections forconducting air to said inlet, means including a normally open valve forconnecting the inlet to one of said connections, means for connectingthe inlet with the other of said connections, a normally closed valve insaid last named means, and means for closing the first valve and foropening the second valve to transfer the inlet from the one connectionto the other connection, said last named means comprising a fluidpressure actuator and a governor operable upon a predetermined rise inpressure in said reservoir for subjecting said actuator to reservoirpressure.

15. A compressed air system comprising a compressor having an inlet andan outlet, a reservoir for the storage of air compressed by saidcompressor, conduit means constantly connecting said outlet andreservoir at all times, an intake connection for conducting air to saidinlet, a normally open valve in said connection, a fluid pressureactuated member cooperating with said valve to close the same, unloadingmechanism for said com-v References Cited in the file of this patentUNITED STATES PATENTS 930,989 Richards Aug. 10, 1909 1,433,607 HarrisOct. 24, 1922 2,275,364 Harris Mar. 3, 1942 FOREIGN PATENTS 23,840 GreatBritain 1912 415,319 Great Britain 1934

